我嘗試構建一個填充列表視圖的異步任務。當我嘗試,並與設置我的ListView與findViewBYId:無法訪問我的異步任務
ListView lv = (ListView) ((View) c).findViewById(R.id.tastelist);
我得到這個錯誤:
Cannot cast from Context to View
我的整個異步任務類:
public class GetTasteJSON extends AsyncTask
<String, Void, String> {
Context c;
public GetTasteJSON(Context context)
{
c = context;
}
@Override
protected String doInBackground(String... arg0) {
// TODO Auto-generated method stub
return readJSONFeed(arg0[0]);
}
protected void onPostExecute(String result){
//decode json here
try{
JSONObject json = new JSONObject(result);
//acces listview
ListView lv = (ListView) ((View) c).findViewById(R.id.tastelist);
//make array list for beer
final List<BeerData> beerList = new ArrayList<BeerData>();
}
catch(Exception e){
}
}
public String readJSONFeed(String URL) {
StringBuilder stringBuilder = new StringBuilder();
HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(URL);
try {
HttpResponse response = httpClient.execute(httpGet);
StatusLine statusLine = response.getStatusLine();
int statusCode = statusLine.getStatusCode();
if (statusCode == 200) {
HttpEntity entity = response.getEntity();
InputStream inputStream = entity.getContent();
BufferedReader reader = new BufferedReader(
new InputStreamReader(inputStream));
String line;
while ((line = reader.readLine()) != null) {
stringBuilder.append(line);
}
inputStream.close();
} else {
Log.d("JSON", "Failed to download file");
}
} catch (Exception e) {
Log.d("readJSONFeed", e.getLocalizedMessage());
}
return stringBuilder.toString();
}
}
錯誤出現在表示'((View)c).findViewById(R.id.tasteList)'的行中。您的圓括號表示將上下文c轉換爲視圖。也許嘗試'((ListView)c.findViewById(R.id.tasteList))' – bbill
是的,當我只是爲了c.finViewById eclipse告訴我把它轉換到一個視圖... – Mike
對。我編輯了我的評論。我認爲Eclipse會在錯誤的位置添加演員。您應該只需要ListView強制轉換的附加括號。 – bbill